Combination switch and variable resistor adapted for use with printed wiring



Nov. 5, 1957 w. H. BUDD 2,812,400

COMBINATION SWITCH AND VARIABLE RESISTOR ADAP'I'ED FOR USE WITH PRINTEDWIRING Original Filed Dec. 4, 1953 4 Sheets-Sheet i G is Jkdwfad 115217211? JrClEvudc? W. H. BU -SW ADAPTED FOR Original Filed Dec. 4,1953 DD 2,812,400 ITCH AND VARIABLE RESISTO USE WITH PRINTED WIRING 4Sheets-Sheet 2 Nov. 5, 1957 COMBINATION Nov. 5, 1957 w. H. BUDD 2,8

COMBINATION SWITCH AND VARIABLE RESISTOR ADAPTED FOR USE WITH PRINTEDWIRING Original Filed Dec. 4, 1953 4 Sheets-Sheet 3 7.21592"? 121B uddw. H. BUDD 2,812,400 COMBINATION SWITCH AND VARIABLE RESISTOR Nov. 5,1957 ADAPTED FOR USE WITH PRINTED WIRING 4 Sheets-Sheet 4 Original FiledDec.

Q 55 Jmkmfnl mlberi .Ev dc? 3 v 1km 2,812,400 Patented Nov. 5, 1957COMBINATION SWITCH AND VARIABLE RE- SISTgEIGADAPTED FOR USE WITH PRINTEDWilbert H. Budd, Elkhart, Ind., assignor to Chicago TelepuliggsupplyCorporation, Elkhart, Ind., a corporation rant:

Original application December 4, 1953, Serial No. 396,295. and thisapplication October 3, 1956, Serial No.

7 Claims- (Cl. 200-67) This invention, like that of the copendingapplication, Serial No. 396,295, filed December 4, 1953, of which thisis a division, relates to a combination switch and variable resistor ofthe type commonly used in radio receivers, and has as its generalpurpose to provide a combined switch and variable resistor or volumecontrol especially adapted for use with printed circuits. With printedcircuitry the wiring by which the various components of the receiver areconnected into their circuits is printed upon one face of a panel ofsuitable insulating material. The material used for the printing of thiswiring, of course, must have a high coetficient of conductivity.Electrolytic copper has been found to be quite satisfactory.

The advantages of printed circuits, or prefabricated wiring as it isoften called are numerous, especially for small portable receivers wherespace is at a premium and cost is an exceptionally important factor.More and more manufacturers of radio receivers are, therefore, adoptingprinted wiring, but since past methods of conmeeting the components of areceiver into their respective circuits are not adapted to this newwiring technique, its adoption has presented the manufacture of thevarious components with a serious problem. This problem was especiallyperplexing where the switch and a variable resistor, often the volumecontrol, are combined in a single composite unit to be controlled by oneshaft. For the variable resistor alone, suitable terminals could beeasily provided to project forwardly in the general direction of thecontrol shaft so as to extend through openings in the panel upon whichthe wiring is printed and be soldered to their respective leads.

However, where switches are combined with and mounted upon a back of avariable resistor, the design found most acceptable through years ofexperience, it was impracticable to resort to the obvious expedient ofmerely lengthening the switch terminals and bending them so as toproject forwardly far enough to reach through the panel upon which thewiring is printed. Such a construction would be highly impractical sinceit would require a very special terminal with a number of bends in it toclear the switch and control covers and so constructed it would lack thenecessary mechanical strength and be difiicult to assemble with thepanel due to the long unsupported length of the terminals.

This invention solves the problem in a novel and expeditious manner bythe rather simple expedient of using a miniaturized variable resistor orcontrol in a housing or casing designed for a full sized control and inmounting the resistor and a switch which is carried on the back of thecontrol housing off center with respect to the housing. This enables theswitch terminals to be brought forwardly directly through the housingand the base of the control, so that the switch terminals as well as theterminals of the variable resistor are supported by the base of theresistor and project directly therefrom.

An important object of this invention thus resides in the provision of acombined switch and variable resistor wherein the switch terminals aswell as the terminals for the resistor lie wholly within the boundary ofthe base for the variable resistor, bearing in mind that, as iscustomary in such controls now in use, the terminals for the resistorare secured to and project from a terminal support which extendsradially out from one edge of the base.

Another object of this invention is to provide a combincd switch andvariable resistor of the character described wherein the switchterminals are protected by being located within the switch and controlhousings, and have their outer end portions supported by and protrudingfrom the base of the control. This arrangement possesses the advantageof holding all of the terminals in proper positional relationship withone another and thus facilitates assembly of the device upon a printedcircuit panel.

Another object of this invention is to provide an improved stationaryswitch contact and terminal especially adapted for use in a combinedswitch and variable resistor designed for use with printed circuitry.

Still another object of this invention is to provide an improved switchconstruction which, though especially designed for incorporation in acombined control unit of the character described, has considerableadvantage from the standpoint of a switch per se.

With the above and other objects in view, which will appear as thedescription proceeds, this invention resides in the novel construction,combination and arrangement of parts substantially as hereinafterdescribed and more particularly defined by the appended claims, it beingunderstood that such changes in the precise embodiment of thehereindisclosed invention may be made as come within the scope of theclaims.

The accompanying drawings illustrate two complete examples of thephysical embodiment of the invention constructed according to the bestmodes so far devised for the practical application of the principlesthereof, and in which:

Figure 1 is a longitudinal sectional view through a combined switch andvariable resistor embodying this invention and illustrating the samemounted upon a printed wiring panel;

Figure 2 is a sectional view taken through Figure 1 on the planes ofline 2-2;

Figure 3 is a front view of the combined switch and volume control ofthis invention;

Figure 4 is a fragmentary detail view illustrating the rear or insideface of the terminal support of the variable resistor and showing themanner in which the ends of the resistance element and the terminals aresecured in position thereon;

Figure 5 is a perspective view of the combined switch and volume controlbut with the switch contactor assembly and the mechanism of the variableresistor removed so as to better illustrate the manner in which thecombined stationary switch contacts and terminals are arranged and passthrough the housing of the resistor;

Figure 6 is a front view of the switch per so fully assembled;

Figure 7 is a view partially in side elevation and partly inlongitudinal section of a combined switch and volume controlillustrating a modified embodiment of the invention;

Figure 8 is a perspective view illustrating the interior of the switchshown in Figure 7 and the back wall of the housing or casing for thevolume control and upon which the switch is mounted in use;

Figure 9 is a front view looking into the switch of Figures 7 and 8, andillustrating the same in its closed condition; and

Figure 10 is a view similar to Figure 9 but showing the switch in itsopen condition.

Referring now more particularly to the accompanying drawings in whichlike numerals designate like parts throughout the several views, thenumeral 5 designates generally a variable resistor or volume control ofmore or less conventional design, and the numeral 6 designates generallya switch of the type covered in U. S. Patent No. 2,660,651, issuedNovember 24, 1953. These two components are mounted in tandem with theswitch 6 secured to the back wall 7 of the cup-shaped cover or casing 8for the volume control.

As is customary, the variable resistor or volume control has a base 9 ofinsulating material which coacts with the cover or casing 8 to house themechanism of the volume control, the cover being secured to the base byears 10 which extend from the front edge thereof and are clinched overthe front face of a combined grounding and mounting plate 11 overlyingthe front of the base 9. This plate 11 has a bushing 12 thereon in whicha control shaft 13 is journalled. It also has a pair of oppositemounting lugs 14 which are adapted to project through holes in a panel15 upon which the entire instrument is mounted and be twisted to securethe instrument in place thereon.

The control shaft 13, as is customary, passes through the bushing 12 andthrough an appropriate opening in the base 9 to mount the rotatingassembly 16 of the variable resistor or volume control. This rotating assembly 16 is of conventional construction and includes inner springcontact fingers 17 which ride upon a collector ring 18 and outer springcontact fingers 19 which ride upon a resistance element 20. Theresistance element as is customary is substantially a flat ring, and ismounted upon the back or inner face of the base 9 concentrically to theshaft 13. Radially outwardly projecting end portions 21 on theresistance element overlie a radially outwardly projecting terminalsupport 22 integral with the base 9, and are clamped thereto by theattachment of the end terminals 24 of the variable resistor. Theseterminals project forwardly from the support 22 substantiallyperpendicularly therto.

The collector ring 18 has the center terminal 25 of the variableresistor formed integrally therewith and secured to the base 9 in theconventional manner to project forwardly from its terminal support 22parallel with the end terminals 24 and the control shaft 13. Hence, whenthe instrument is mounted on the back of the panel 15 with the base 9,which constitutes the front wall of the device, in juxtaposition to therear of the panel, the terminals 24 and 25 protrude through appropriateopenings in the panel to enable the ends thereof to be soldered to thewiring (not shown) printed upon the front face of the panel.

The rearward thrust imposed upon the rotating assembly by the springcontact fingers l7 and 19 is carried by a conventional C washer 26seated in a groove in the shaft and bearing against the front end of thebushing 12.

The rotating assembly includes a drive arm 27 from which a switchactuating lug 28 and a stop lug 29 project rearwardly. The latterco-acts with a stationary stop abutment 30 to define the limits ofrotation of the rotating assembly. The switch actuating lug 28 co-actswith a cam 31 which forms part of a pitman-like switch actuator 32 toopen the switch during the final degrees of retrograde rotation of thecontrol shaft. The actuator is guided for reciprocation by havingopposite end portions thereof slidably received in openings in theopposite side walls of a stamped metal cover or casing 33 which co-actswith a base 34 of insulating material to provide a cup-shaped housingfor the switch.

The stamped metal casing 33 has the customary mounting ears 35 by whichthe switch is secured to the back wall of the volume control cover orcasing 8, this wall having a relatively large substantially rectangularopening 36 to accommodate the portion of the actuator 32 which carriesthe cam 31, and also to permit the terminals 37 of the switch to projectforwardly into and through the housing of the volume control. Since thespecific construction of the switch in that embodiment of the inventionillustrated in Figures 1 through 6, inclusive, forms no part of theinvention, further detailed description thereof is deemed unnecessary.It is sufiicient to point out that the contactor 38 which is like thatof U. S. Patent No. 2,698,369, issued December 28, 1954, is confinedbetween the inner face of the base 34 and a contact driver 39 isdrivingly connected to the actuator 32 by means of 2. lug 40 and to thecontactor 38 by lugs 41.

Consequently, a spring 42 reacting between a shoulder on the actuatorand the side of the casing 33 yieldingly urges the contactor intobridging engagement with the stationary contacts 43 of the switch in themanner brought out at length in the aforesaid U. S. Patent No.2,660,651.

Each stationary switch contact and its terminal is one integralsubstantially L-shaped sheet metal stamping having a foot portion 44 anda leg extending upwardly therefrom and providing the terminal 37. Asbest shown in Figure 5, the leg portion of the stamping is bent atsubstantially right angles to its foot portion and both of these partsof the stamping have one continuous coplanar bottom surface or edgewhich rests upon the base 34. Two spaced attaching ears 45 project downfrom the bottom of the foot portion 44 to pass through the base 34 andbe split and staked over at the opposite side thereof as at 46.

The combined switch and terminal stampings are thus firmly anchored tothe base with their terminal portions 37 near and substantially parallelwith the adjacent side wall of the casing 33 and also the adjacent sidewall of the casing 8. To accommodate the contact spring 42 and theportion of the pitman upon which it is mounted, the terminal portionsare cut out as at 47. The actual contacts 43 are provided by what may beconsidered the toe portions of the stampings, and are curved to provideconi vex surfaces facing one another and perpendicular to the base, itbeing understood that the contactor 38 moves between and into engagementwith these convex surfaces as the switch closes.

The outer end portions of the terminals 37 are reduced in width toprovide abrupt shoulders 48 so spaced from the base 34 that when theparts are assembled with the narrow outer end portions of the terminalspassing through holes 49 in the base 9, these shoulders bear against theinner face of the base 9. The switch terminals are thus firmly heldagainst displacement from their correct positional relationship with thecontrol shaft and the terminals 24 and 25 of the volume control.Consequently, during mounting of the instrument upon the panel 15 all ofthe terminals will align with their respective holes in the panel.

It is to be understood that when the instrument is thus assembled withthe panel its attaching cars 14 are twisted to hold the instrumentthereon. Thereafter, all of the terminals may be easily soldered totheir respective leads or wires printed on the front face of the panel,by any one of the various methods employed by the differentmanufacturers to effect such soldering.

It is to be observed that by virtue of the off center position of thecontrol and switch with respect to their respective housings, space isafiorded within the housings and particularly within the control housingto accommodate the switch terminals, it being understood that the switchterminals lie outside the periphery of the circular resistance element20 where maximum space obtains between the resistance element and theadjacent wall of the cover 8. In other words, the parts are so arrangedthat the switch terminals 37 are equispaced from the plane of maximumeccentricity.

In that form of the invention illustrated in Figures 7 to 10 inclusive,the switch embodies certain features which adapt it particularly well tothis invention. Thus, instead of the stamped and formed combinationterminal and contact of the previously described form of the invention,the stationary switch contacts 50 and their terminals 51 are provided bycylindrical pins or posts, the contacts consisting merely of cylindricalflanges thereon so located asto seat upon the base when the mounting endof the pin or post protrudes through the base the correct distance to berolled over or riveted. This construction has the advantage of adaptingthe combined contact and terminal to automatic feeding apparatus andthus achieves an assembly cost reduction. It also achieves exceptionalstability for the mounting and assures that the terminals will projectstraight out from the switch base to pass through relatively small holes52 in the back wall 53 of the metal cover or casing for the volumecontrol, and through close fitting holes in the base 9 of the volumecontrol.

This modified switch construction simplifies the guiding of theinsulated contact driver 54 by utilizing the terminals to guide thesame. To this end, the driver 54 has a tongue 55 projecting therefrom tomove between the terminals as best shown in Figure 9. Shoulders 56 onthe driver at the base of this tongue engage the terminals 51 to limitthe spring produced movement of the contact assembly and therebypreclude excessive deflection of the contactor arms. Retraction of thecontact assembly is of course, effected in the same manner ashereinbefore described, namely, by the drive lug 28 riding onto the cam31.

From the foregoing description taken in connection with the accompanyingdrawings, it will be readily apparent to those skilled in this art thatthis invention solves the problem of adapting a combined switch andvolume control to use with printed circuitry, and that the man ner inwhich this objective is attained by this invention results in a highlypractical and easily mounted instrument.

What is claimed as my invention is:

1. An electric switch comprising: a cup-like housing having acylindrical side wall and an end wall of insulating material closing oneend of the housing and providing a base for the switch, the other end ofthe housing being open; a movable contactor wholly within the housingand constrained to movement across the inner face of the base; actuatingmeans for the movable contactor, inside the housing but accessible formanipulation through the open end of the housing; stationary contactsfixed on the switch base inside the housing to be engaged by the movablecontactor; and terminals carried by the base and electrically connectedwith the stationary contacts, said terminals being positioned whollyinwardly of the periphery of the base and projecting from the basetowards and through and beyond the open end of the housing to passthrough appropriately located holes in a wall upon one side of which theswitch may be mounted with said wall closing the open end of thehousing, and thus provide for connecting the switch with conductors atthe other side of said wall.

2. The switch of claim 1 wherein said terminals are cylindrical postsand the stationary contacts are flanges on said posts, and wherein saidposts are fixed to the switch base by having their portions inwardly ofthe flanges passing through the base and rolled over the opposite facethereof to thereby clamp the flanges against the base.

3. A combined contact and terminal unit for an electric switch,comprising: a substantially L-shaped sheet metal stamping providing anelongated foot having a flat bottom surface engageable with a switchbase, and an elongated leg extending up from one end portion of saidfoot substantially perpendicular to its flat bottom surface,

said leg providing a terminal; a contact portion at the other end ofsaid foot having a contact surface substantially normal to said fiatbottom surface; and attaching lugs on said foot extending downwardlytherefrom substantially perpendicularly to said surface, for securingsaid foot to a switch base.

4. The combined contact and terminal unit set forth in claim 3 whereinsaid end portion of the foot from which the terminal projects isdisposed at an acute angle to the foot and has a surface thereoncoplanar with said fiat bottom surface on the foot to increase thestability of the unit upon securement thereof to a switch base.

5. A combined stationary contact and terminal unit for an electricswitch, comprising: a substantially L-shaped sheet metal stamping havingan elongated mounting member and an elongated leg providing a terminalintegrally joined to one end portion of the mounting member andextending generally perpendicularly therefrom, said mounting memberhaving fiat parallel sides and opposite longitudinal edges substantiallynormal to said sides and from one of which edges the terminal projects;means on the mounting member remote from the terminal providing acontact portion having a contact surface substantially normal to theedges of the mounting member; and lugs spaced along the length of saidmounting member and projecting from the other edge thereof, in the planeof the sides of the mounting member, for attaching the combined contactand terminal unit to a switch base.

6. The combined stationary contact and terminal unit set forth in claim5 wherein said end portion of the mounting member from which theterminal projects is bent flatwise out of the plane of the mountingmember sides at an abrupt angle thereto to steady the mounting member onthe base.

7. In an electric switch of the character described: a flat base ofinsulating material; a pair of stationary contacts on said base andhaving opposing contact surfaces projecting up from said basesubstantially perpendicularly thereto; terminals for said contactsprojecting upwardly therefrom; a bridging contactor slidable across thebase to and from bridging engagement with said opposing surfaces of thestationary contacts; an insulated driver for the contactor overlying thesame and having driving engagement with the contactor; an actuator forthe driver constrained to linear motion along a path parallel to theflat base and intersecting the space between the opposing con tactsurfaces; a loose driving connection between the actuator and thedriver; and a projection on the driver having sliding engagement withthe terminals so that the motion of the contactor assembly is guidedjointly by the driving connection between the actuator and the insulateddriver and the movement of the projection on the driver between theterminals.

References Cited in the file of this patent UNITED STATES PATENTS1,999,019 Hall et al Apr. 23, 1935 2,160,142 Hathorn May 30, 19392,264,955 Schellenger Dec. 2, 1941 2,612,577 Jacobi Sept. 30, 19522,698,369 Bailey et a1 Dec. 28, 1954 2,717,943 Bailey et al Sept. 13,1955

